(a) Field of the Invention
This invention relates to the production of hydrocarbons, water and other products from a fixed-bed carbonaceous deposit such as well characterized in oil shale deposits, in coal bed deposits, in tar sand deposits and other geological formations found in the western United States and Canada and more specifically, but not by way of limitation, to an in-situ production system for the extraction of hydrocarbons and other products in an oil shale deposit. The production system uses a plurality of injection wells and production wells with a thermal energy carrier fluid, called herein “TECF”. The TECF is used to create a porous heating element in a horizontal or near-horizontal highly-permeable zone for retorting hydrocarbons from the highly-permeable zone and adjacent less-permeable zones.
(b) Discussion of Prior Art
Heretofore, most prior-proposed, in-situ oil shale retorting technologies are dependent on oil shale rock formations for radial transmission of thermal energy Btu's from the wall of a well bore out into the surrounding rock. In this type of radial geometry, heat flow outwardly from a very small porous heating element surface area of a well bore wall (i.e., about 2 to 3 square feet per foot of well bore porous heating element length), the Btu's heat flow rate is very limited. This limited, heat flow rate per well bore thereby requires drilling a large multiplicity of closely spaced well bores to achieve economic production rates. Such a requirement for a multiplicity of closely spaced well bores is environmentally unacceptable and is economically very cost/price limiting.
The subject oil shale production system is based on the injection, from a line of injection wells, of TECF as volatilized hot vapors, into either a horizontal or near-horizontal, natural-occurring, highly-permeable zone or a horizontal or near-horizontal, highly-permeable hydraulic fracture zone to create a desired, very large porous heating element in an underground surface area. The surface area of the large porous heating element provides a means for economic, in-situ retorting hydrocarbon form a carbon-rich, oil shale geologic formation,